The invention relates to a panel particularly but not exclusively a removable side or door panel for mounting on a frame of an electrical cabinet of the type used to receive electronic and/or electrical components.
Electrical cabinets are commonly used in the operation of local data networks. Components such as subracks carrying electronic and electrical circuitry, fans and other accessories are mounted within the cabinet on the internal frame. The frame is then clad with side panels and an openable door panel. These side panels and the door panel need to be easily fittable to the frame and detachable therefrom, to facilitate the initial mounting of components on the frame and their subsequent in-use servicing.
Current electrical cabinets have removable side and door panels which are quite heavy for a person to lift on and off the frame, in view of the large area of the sheet metal used to form the panel (a typical panel can be 2 meters tall and up to 1 meter wide) and the thickness or gauge of the sheet metal (typically 1.5 mm, but always in excess of 1 mm).
A known removable door panel produced by Vero Electronics Limited comprises a sheet of metal of 1.5 mm thickness folded to define an elongate main panel section along the vertical edges of which are longitudinal side flanges and along the horizontal top and bottom edges of which are transverse end flanges. The longitudinal side flange at the hinge side of the panel is along its full length folded back towards the main panel portion and has a foot which is secured to the main panel portion to define a closed rectangular box section which acts as an edge reinforcement up along the hinge side of the door panel. The top and bottom ends of this closed box section are not attached to the top and bottom horizontal end flanges of the panel. Consequently, the door panel is poor at resisting torsion about the longitudinal axis of the panel. The primary purpose of the closed-box section is to provide longitudinal bending rigidity.
As an alternative constructional technique used in known door and side panels, it is possible to add separate stiffeners which provide the desired torsional and longitudinal bending rigidity, but the use of such extra components increases the manufacturing cost and complexity.
According to one aspect of the present invention there is provided a panel comprising a sheet of metal folded to define an elongate main panel portion along the edges of which are a first longitudinal side flange and a first transverse end flange, wherein:
the first longitudinal side flange is along at least part of its length folded back towards the main panel portion and secured thereto to provide a tubular edge reinforcement of the panel: and
the first longitudinal side flange has a first longitudinal end which is secured to the first transverse end flange.
The securing of the first longitudinal side flange to the first transverse end flange provides improved torsional rigidity about the longitudinal axis of the panel. This removes the need to use separate components, such as stiffeners, to provide the rigidity. Thus, the manufacturing process is reduced in cost and simplified.
Also, it becomes possible to use metal sheet which is thinner than previously used. For example, the thickness of the sheet of metal may be 0.9 mm or less, more preferably 0.8 mm or less, more preferably 0.7 mm or less, more preferably 0.6 mm or less, or even more preferably 0.5 mm or less.
Preferably, the first longitudinal end of the first longitudinal side flange is secured to the first transverse end flange at a plurality of locations along the first transverse end flange. The increased number of rigid connections between the two flanges provides increased torsional rigidity. This is particularly true if the connection locations are widely spread, apart along the first transverse end flange.
Conveniently, the flanges are rigidly connected together by spot welding. Alternatively, seam welding could be used. In some embodiments, it is even possible that gluing using structural adhesives might be acceptable.
Preferably, the first transverse end flange is along at least part of its length folded back towards the main panel portion and secured thereto to provide a tubular edge reinforcement of the panel. This assists the panel in resisting transverse bending.
Preferably, the sheet of metal is folded to define a second transverse end flange at the opposite end to the first transverse end flange, and the first longitudinal side flange has a second longitudinal end which is secured to the second transverse end flange. By having rigid connections between the first longitudinal side flange and the two transverse end flanges at both ends of the panel, the torsional rigidity is increased yet further.
Preferably, the sheet of metal is folded to define a second longitudinal side flange at the opposite side to the first longitudinal side flange; the second longitudinal side flange is along at least part of its length folded back towards the main panel portion and secured thereto to provide a tubular edge reinforcement of the panel, and the second longitudinal side flange has first and second longitudinal ends which are secured to the first and second transverse end flanges respectively. The resulting panel has very good resistance to torsional bending about the longitudinal panel axis, in view of the rigid connections at all four corners of the panel between the side and end flanges.
According to a further aspect of the present invention, there is provided an electrical cabinet comprising a frame for receiving electronic and electrical components, and one or more removable side panels as described above and/or a removable door panel as described above.